This proposal requests a renewal of funding for the Mexican Migration Project to gather and disseminate high quality data on documented and undocumented Mexican migration to the United States. The MMP has been in the field since 1982 and from 1987 onward has received continuous funding from NICHD. The database has become a mainstay for research on Mexican migration to the United States and a model for similar data collection efforts in China, Poland, Ukraine, West Africa, Morocco, Bangladesh, and elsewhere in Latin America, yielding a growing body of data collected using comparable methods and instruments (see Massey and Capoferro 2004). The MMP initially focused on west-central Mexico-the states of Guanajuato, Jalisco, Michoacn, San Lus Potos, and Zacatecas. These states have consistently accounted for at least half of all migrants to the United States and represent the historical heartland for U.S.-bound migration. During the 1990s, however, new migration sources emerged in response to structural changes in the Mexican political economy and MMP investigators expanded data collection geographically to include new sending regions throughout the country, eventually compiling samples from 24 of Mexico's 32 states. Together these states account for almost 90% of all undocumented migrants who registered for Mexico's consular ID card (Massey, Rugh, and Pren 2010). At this point, the most serious geographic omission in the MMP database is Mexico's Federal District, which accounts for around 7% of all undocumented migrants who registered for the consular ID card. In the coming period this gap will be filled by surveying neighborhoods in Mexico City. Given recent declines in the likelihood of undocumented departure and the rising frequency of circulation in legal status, we also propose to survey new communities in west-central Mexico, as this region offers the longest history of migration and the largest stock of migratory experience to assess the nature and reasons for trends over time. At the same time, we also will continue to conduct surveys in new origin areas located in Mexico's central region. We also propose to use an innovative new approach to improve coverage of the large population of undocumented migrants living in the United States and will add new questions to the survey instrument to assess the effect of violence on migration to the United States, and also to phase in a new team of investigators capable of leading the project into the future.